1. Field of the Invention
The invention relates to blind fasteners; and, more particularly, to blind fasteners and method for forming same for installation in aircraft structure having a threaded nut threaded on a threaded stem member, torque between the stem member and the nut being provided without damage to the internal threads of the nut and external threads of the stem member.
2. Description of the Prior Art
High-strength structural blind fasteners for use in airplanes, rockets and the like are described and claimed in U.S. Pat. No. 3,643,544. In that U.S. Patent to Massa, assigned to the predecessor in interest of the same assignee of this application, a blind fastener for installation in aircraft structures or the like is disclosed comprising a threaded screw having a screw head at one end and an internally threaded nut threaded on the other end, the nut having a head at one end and a tapered portion at the other end. A deformable sleeve is disposed on the stem member abutting at one end against the stem head and at the other end against the tapered portion of the nut. After assembly of the fastener components, indents are provided in the outside of the nut body deforming or distorting both the internal threads of the nut and the external threads of the stem member to provide a torque between the nut and stem member. These indents distort the threads in the area of such indentation and, as a result, there is a tendency for the threads to want to strip. The end result is that the fastener may not be able to carry as much load as possible and may unscrew during vibration. There is a need for providing the torque necessary for such fasteners without distorting the threads. Such a feature would enable the fastener to carry more load than known prior art fasteners and would not unscrew during vibration.